Rong Li,Xiao-Sen Li,Zhao-Yang Chen,Yu Zhang,Chun-Gang Xu,Zhi-Ming Xia
Tetra-n-butyl ammonium bromide (TBAB) was widely used in the research fields of cold storage and CO2hydrate separation due to its high phase change latent heat and thermodynamic promotion for hydrate formation. Agglomeration always occurred in the process of TBAB hydrate generation, which led to the blockage in the pipeline and the separation apparatus. In this work, we screened out a kind of anti-agglomerant that can effectively solve the problem of TBAB hydrate agglomeration. The anti-agglomerant (AA) is composed of 90% cocamidopropyl dimethylamine and 10% glycerol, which can keep TBAB hydrate of 19.3–29.0 wt. % in a stable state of slurry over 72 h. The microscopic observation of the morphology of the TBAB hydrate particles showed that the addition of AA can greatly reduce the size of the TBAB hydrate particles. CO2gas separation experiments found that the addition of AA led to great improvement on gas storage capacity, CO2split fraction and separation factor, due to the increasing of contact area between gas phase and hydrate particles. The CO2split fraction and separation factor with AA addition reached up to 70.3% and 42.8%, respectively.Keywords:CO2separation;TBAB;IGCC;anti-agglomerant;micromorphology;hydrate
By coupling CALF-20 on ZIF-7 via in situ crystallization in the confined micrometer-sized pores of poly(acrylates), a novel composite, namely, CALF-20-on-ZIF-7@poly(acrylates), has been synthesized for the simultaneous removal of CO2 and H2S from IGCC feed gas. Within this coupled crystal, CALF-20, known for its strong adsorption capacity and excellent stability toward CO2 and H2S, serves as the outer layer crystal to shift the adsorption/desorption hysteresis loop of inner ZIF-7 to beyond atmosphere pressure. Under high pressure, CO2 and H2S are automatically adsorbed. Upon reducing the pressure to the atmospheric level, CO2 is automatically released, while H2S remains temporarily due to its high adsorption energy. After about 150 cycles of CO2 adsorption/desorption of the kilogram-scale composite, H2S approaches saturation and is then removed by vacuuming. Since the content of H2S in IGCC feed gas is trivial, the total energy consumption for the composite regeneration is 0.16 MJ/kg (CO2). After 600 consecutive cycles, the CO2 adsorption capability of the composite decreases by 0.41%, demonstrating excellent cyclic stability.
Yongtao Zhang,Zaizheng Jiang,Zhihe Xin,Qingqi Dong,Fei Wang
Traditional coal burning emits a large amount of pollutants, including sulfur dioxide (SO2), nitrogen oxides, and carbon dioxide (CO2), severely contaminating the environment and exacerbating global warming. In contrast, integrated gasification combined cycle (IGCC) technology, with highly efficient and clean characteristics, significantly reduces pollutant emissions and has a positive impact on environmental protection. It is a simple and effective method to obtain hydrogen (H2) by purifying IGCC fuel gas with the main components of H2 and CO2. Thermodynamic promoter tetra-n-butyl ammonium bromide (TBAB) is widely used in gas separation of IGCC fuel gas by the hydrate method. In this work, polystyrene nanoparticles grafted by –SO3– groups (−SO3–@PSNS) and grafted by –SO3– groups and Ag particles (Ag&–SO3–@PSNS) are used together with TBAB, respectively, to promote the formation of hydrate. The gas separation effect and growth morphology are studied. The experimental results demonstrate that the incorporation of nanopolymer can significantly enhance the separation efficiency (SFr) of a mixture of H2 and CO2. Notably, compared to the reaction solution without nanopolymer, 2 mmol/L –SO3–@PSNS exhibits the most pronounced effect on gas separation, resulting in an impressive gas consumption of 0.755 ± 0.323 mmol/L and a remarkable increase in the separation factor (SF) by 106%. After loading silver nanoparticles, the promoting effect of Ag&–SO3–@PSNS is further strengthened. Under Ag&–SO3–@PSNS-20%, the gas consumption reaches the maximum of 0.775 ± 0.003. Under Ag&–SO3–@PSNS-30%, the SF rises from 32.79 ± 6.27 to 37.92 ± 7.19, indicating an impressive increment of 15.80%. The visualized droplet experiment shows that Ag&–SO3–@PSNS significantly promotes the nucleation of hydrate and the growth rate of hydrate.
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